I went to a party store to get a tablecloth, and while I was there I looked around for items that could be made into a pushrod shroud. Here's what I came up with:

Test tube shot glasses

These looked promising, and will work, but they're a bit brittle on the band saw. The bell mouth tends to split and shatter. They give a good variety of lengths depending on the angle you cut them at.

A kazoo and a pen

I know it's a party store, but what are they thinking? The last thing I would buy for a mob of kids is a bunch of kazoos. But when cut at an angle, the kazoo gives a nice oblong shroud, although it's a bit shallow. The multicolor pen, on the other hand, is just about perfect. Cut right down the middle and it gives you two nice covers. It requires just a bit of sanding to eliminate the small hole in the end. Hopefully it will take paint, I don't want a Batman theme on my plane. In the past I have used plastic spoons, just cut off the handle and part of the bowl. They tend to be too small.